Defeat three of the Girsh nephilim in a single playthrough.
Kill three of the six Girsh Nephilim in a single playthrough, abilities of previous killed Girsh Nephilim will be added to the rest of them.
He
Defeat five of the Girsh nephilim in a single playthrough.
Kill five of the six Girsh Nephilim in a single playthrough, abilities of previous killed Girsh Nephilim will be added to the rest of them.
Heat Death
Get vaporized.
To be vaporized your temperature needs to be above 10,000. This can be accomplished with relative ease via being covered in plasma and then detonating multiple thermal grenade mk IIIs on top of your character in quick succession.
Pouring warm static on yourself is potentially irreversible including when using Precognition as the mutation can be removed. However as a truekin, you can always reverse the result via use of a sphynxsalt injector.
Beguiling a creature with an innate ranged attack such as a slugsnout and then standing directly between it and an enemy should be a reliable way to accomplish this.